Bug o’the Week – Elm Sawfly

Howdy, BugFans,

The BugLady got a few “what’s this dynamite caterpillar?” pictures from a friend toward the end of summer – one of a larva, and one of a pupal case in not-very-good shape.  She usually gets “what’s this wasp/fly?” pictures of the equally-distinctive adult in June, like this one from BugFan Andy.

Sawflies are small, primitive wasps (ancestral sawflies were around 250 million years ago) that most people have never heard of, and they usually carry out their business below the radar.  They’re in the large order Hymenoptera (ants, bees, wasps, and sawflies) and in the family Cimbicidae, which includes about 200 species (12 in North America).  Cimbicids lack that famous “wasp waist,” have prominently knobbed antennae, and some of the heftier species can be mistaken for hornets https://bugguide.net/node/view/1544361/bgimage.  Their larvae resemble moth or butterfly caterpillars until you compare eyes (sawflies have fewer) or count legs (sawflies have more).  There have been a number of previous episodes about sawflies – here are two of them: https://uwm.edu/field-station/sawflies-among-us/ and https://uwm.edu/field-station/slug-sawfly-a-skeletonizer/.

With ¾” adults and 2” larvae, the Elm sawfly (Cimbex americana) is the largest (or “among the largest,” depending on who you read) sawfly in North America.  The (usually) blue-black adults are sexually dimorphic (“two forms”).  Females have thickened femurs on the second and third pair of legs, and they usually have pale, wrap-around stripes on the abdomen that don’t quite touch at the midline https://bugguide.net/node/view/610402/bgimage.  Males’ legs are massive https://bugguide.net/node/view/1099589/bgimage, and they may have a red or black abdomen.  Both have smoky wings, orange antennae, and a white spot at the base of the thorax.

As Eric Eaton says in his bugeric blog, “They do not have a stinger.  Both genders simply look intimidating” http://bugeric.blogspot.com/2012/06/wasp-wednesday-elm-sawfly.html.

The pebbly-textured larvae come in a rainbow of colors: https://bugguide.net/node/view/1724940/bgimagehttps://bugguide.net/node/view/1495194/bgimagehttps://bugguide.net/node/view/1421517/bgimagehttps://bugguide.net/node/view/1525493/bgimage, and,

rarely, pink https://bugguide.net/node/view/708165/bgimage,

with a creepy-looking head https://bugguide.net/node/view/1700150/bgimage that looks like something that the BugLady saw in an X Files episode.

These amazing larvae are chemically defended – glands near the spiracles (breathing pores along the sides of the body) produce unwholesome liquids that can be released through the pores.

The “saw” in sawfly comes from the female’s egg laying apparatus, which she uses to make a hole in the underside of a leaf (or twig, say some sources) in late spring.  She may deposit several eggs on one leaf, and she can lay more than 125 of them, total.  True to her name, elm is the main host plant, but she also oviposits on willow (another favorite), and incidentally on maple, birch, willow, basswood, cottonwood, poplars, ironwood, plum, alder, boxelder, and apple.  The larvae eat their host’s leaves, wrapping their rear half around twigs while feeding https://bugguide.net/node/view/1716690/bgimage (and curling up tightly at rest https://bugguide.net/node/view/1006040/bgimage).  When they’re almost-mature, they drop to the ground to make a pupal case in the leaf litter, and they complete their metamorphosis in spring https://bugguide.net/node/view/931802/bgimage.  Or they may decide to stay tucked inside their cocoon until the following spring.

They are vegetarians as larvae and adults.  Adults have sturdy jaws that they use to pierce and even girdle the bark of twigs so they can feed on the sap.  Larvae are attacked by a number of parasites/parasitoids, and larvae and pupae are eaten by mice and shrews.  Populations can be somewhat cyclical, and the larvae may be minor forest pests in peak years, but harm is minimized because they’re feeding late in a tree’s growing season.

Kate Redmond, The BugLady

Bug of the Week archives:

Bug o’the Week – Spinybacked Orbweaver– A Spider for Snowbirds

Greetings, BugFans,


This episode is dedicated to BugFan Tom.  Tom has a day job, practices suburban agriculture afterwards, and conducts field research by night, so the BugLady really appreciates his fitting spider studies into his off time.  He has an insatiable curiosity – and a camera – and he provided many pictures and lots of wonderful running commentary and deep thought about a cast of backyard spiders that he got to know personally (his BugFan wife suggested that he may have taken more pictures of those spiders than of his offspring’s childhood, a complaint that the BugLady’s parents would have been sympathetic to).


As Tom says, “There is a lot going on here, which is why they need eight legs.”


Ask a birder what a snowbird is and they’ll tell you it’s a Dark-eyed Junco, a bird whose idea of “flying south in winter” may only bring them from their nesting grounds in Canada to bird feeders here in God’s Country (though some do reach the Gulf Coast); 844 juncos were tallied during the Riveredge Nature Center Christmas Bird Count on Dec. 14.  Ask Chambers of Commerce of communities along the southern edge of the US what a snowbird is, and they’ll tell you that snowbirds are Northerners who fly south for the winter months.  If you’re a snowbird, check the bushes, orchards, edges, and gardens from the Deep South and the Caribbean west through southern California, and south into South America for these unique spiders; you won’t find them in Wisconsin.

They’re called Spinybacked Orbweavers (Gasteracantha cancriformis), in the orb weaver family Araneidae.  According to bugguide.net, “gaster” and “acantha” are Greek for “belly” and “thorn,” and “cancriformes” is Latin for “crab-shaped.”  Not surprisingly, they’ve picked up lots of common names – Crab-like Spiny/Crab-like Orbweaver, Jewel Box/Jewel Spider, Spiny-bellied Orbweaver, Smiley Face Spider, and Crab Spider (though they’re not related to our goldenrod crab spiders in the family Thomisidae).  Early taxonomists sometimes mistook the different color variations for separate species.

Tom’s great macro photography makes them look larger than they are – females are about a half-inch long and a little wider, and males are much smaller.  Females have six, sturdy spines on their abdomens, and males are just lumpy https://bugguide.net/node/view/1111533/bgimage.


Males court warily in fall, first hanging from her web by a thread, and then tapping in a four-tap rhythm.  He approaches her, and she responds by wrapping him in silk (her favorable response apparently starts out the same as her unfavorable response would) and, with the web vibrating, they copulate.  He staykus at her web afterwards and dies six days later.  She sits in her webs, making an egg sac that contains as many as 260 eggs, then she spins a silk pad on to the underside of a nearby leaf, and fastens the egg sac to it.  She covers it with cream-colored or yellow silk, runs a dark green silk line down the center, and finishes it with a canopy of coarse, green threads.  When the protective case is finished, she dies

The spiderlings overwinter and hatch within the silken nest, finally exiting by February (southern climes, remember?)  The BugLady found several different phenologies for Spinybacked orbweavers – they are, alternatively, present in the egg case in November through January and as spiderlings and adults for a few months after that; present as adults over winter until they reproduce in spring; or, in Florida, present all year as adults (females), or present except in December and January (males).  Tom, in Mississippi, sees eggs sacs in October and early November and doesn’t start seeing the webs until mid-spring.  The BugLady suspects that location must be the key.


Like almost all spiders, they’re (mostly) carnivorous, feeding on the small insects that fly into their webs.  The catch of the day may be eaten immediately or paralyzed, wrapped, and stored.  BugFan Tom wrote about dodging biting flies by ducking under spider webs.  The hard carapace and spines make her unappealing to predators, but her egg cases do get parasitized.

Two things about the Spinybacked orbweaver:


First – Why?  A brightly-colored spider with spines sharp enough to puncture human skin if handled roughly (her bite isn’t dangerous).  Form is function – the sturdy spines certainly discourage birds and other large predators, and one source mused that it would be tough for a solitary wasp to drag a spiny spider underground to provision its young.  But, why red, orange, yellow and white?  The “prey attraction hypothesis” says that spider prey is attracted to the bright colors, but research does not support this – spiders that were painted black captured more prey.  The bright colors are more likely “aposematic” (warning) coloration.   Some color forms may be regional.


Second – so much has been written about that wonderful web.  She spins a new one every night (Tom observed one spider at work on a new web before 7:30 AM and wrote “So I still have no idea when she dismantles the capture spiral from the previous day. I have to sleep sometime.”), and she will sometimes destroy her web in a rainstorm, gathering it into a glob that she presses to her mouth before discarding it (she may be harvesting both moisture and nutrients from it).

Here’s Tom’s description of a web in progress: “Check out the attached image. This is the right side of her web, she is moving clockwise (toward the ground on this side of the web), and has just attached a strand to the radial immediately above her and is reaching out to grab the next one, which is barely visible to her left, and toward the bottom of this shot. Notice that the radial to which she has just attach a new capture spiral strand is not straight, but is bent (stretched) downward toward her just to the right (from your perspective) of her rightmost rear leg. You can see the new length of capture spiral extending from her spinneret back to the previous radial. Now, check out the point where the radial is ‘bent’ toward the ground, as described previously. There you can see a fine strand extending vertically to the top of the slide, and downwards toward and beneath the spider, though I cannot see it clearly beyond the spider and to the bottom of the slide. This is, I believe, a pre-capture spiral (might not be the right name), and these are mainly not visible to the naked eye, or to mine at least. She moves along these and the radials as she lays new capture spiral, pulling the radial toward her, attaching the new line, then releases the radial and moves to the next.


She deposited about 40 new lines within the capture spiral, but did not continue these to the center of the web, and next attached bird visibility tufts to the otherwise bare radials extending to the center of the web.

Webs are formed at a slight angle to the ground, in vegetation or on structures (males stay near female’s webs).  At the center is a disc where she rests, and she may extend as many as 30 radii.  She leaves a gap just outside the center, and then she starts spinning the sticky “capture spiral,” working clockwise (Tom had one ambidextrous spider that sometimes worked counter-clockwise), and the capture spiral may be two feet across (half-inch spider, remember).  Females orient themselves in the web “belly up,” with their backs toward the ground, presenting a dark surface in the central disc; it’s not certain if this is for camouflage/counter-shading or for thermoregulation.

They attach little white tufts of silk to the web, and there’s much discussion about that.  Do they make the web more conspicuous (web advertisement), so larger animals can see and avoid it, like the zigzag stabilimentum in the web of a Black and yellow orb weaver/garden spider?  Or, do the tufts reflect UV rays and attract prey?


Researchers Gawryszewski and Motta painted the white tufts black and saw no change in the quantities of prey captured, and the painted webs didn’t get damaged any more or less frequently than unpainted.  They reject both hypotheses and “propose that silk tufts might be an aposematic signal.


Here’s a neat article about comparative web-spinning techniques in orb-weavers: https://www.conservation.unibas.ch/team/zschokke/pdf/zschokke1995eje.pdf


Thanks a million, Tom.


Kate Redmond, The BugLady

Bug of the Week archives:

Bug o’ the Week – And Now for Something a Little Different VII – Attack of the Killer Shrews

Howdy, BugFans,


This is a revised version of an article that the BugLady wrote for the winter, 2013-14 issue of The BogHaunter, the newsletter of the Friends of the Cedarburg Bog, an organization that partners with UWM and the DNR to educate people about the Bog and to preserve it.  The Bog is the BugLady’s church and her shrink.


Northern short-tailed shrews (Blarina brevicauda) are one of the most common small mammals between the Great Plains and the Atlantic, but they are rarely seen.  In winter, when they aren’t sheltering in out-buildings, they’re found in the intranivean and subnivean layers – the spaces between the ground and the top of the snow.  The meandering, inch-wide tunnels they make just below the snow’s surface offer some protection from predators, though foxes and owls can hunt by ear, and shrew bones are common in owl pellets.


Largely nocturnal in summer, they spend the daylight hours under rocks or logs, in leaf litter, and as deep as 20 inches underground in tunnels that they dig with their front paws (they also use burrows made by voles and moles).  In winter, they hunt during the balmier daylight hours.  They’re habitat generalists.

A short-tailed shrew’s winter diet includes mice, voles, and other shrews.  In warm weather, they add insect larvae (shrews can be valuable controllers of pest insects), snails, slugs, earthworms, crickets, salamanders, snakes, and even small birds to their diets.  They eat some roots, seeds and berries year-round, and they may also scavenge on dead animals.  They usually dine underground, and they are known to cache food caught when they’re full, for use in leaner times.


Shrews are always operating in overdrive; their heart rate of 800 to 1300 beats per minute exceeds that of a hummingbird, which goes from 250 beats per minute at rest to 1250 in flight.  Their high metabolism requires them to feed every two to three hours and to eat up to three times their weight daily in order to keep going. They hunt for about five minutes out of every 30.


Because they have glands that produce poisonous saliva (few other mammals do), short-tailed shrews can pick on critters their own size.  The venom isn’t injected through hollow fangs; the shrew has to gnaw on its victim a bit.  The venom, a neurotoxin, slows their prey’s heart and respiration rate and can kill them or can paralyze them for future use.  Short-tailed shrew bites are dangerous for dogs and cats, and even humans experience burning and significant swelling at the site of a bite.


Although they look mouse-like, short-tailed shrews are not rodents, but are grouped with moles in the order Insectivora.  They are three to four inches long (males are a bit larger than females) plus an inch-long tail that they hold up in the air as they travel (they walk on those short legs, rather than hopping), and they weigh about an ounce.  They have a pointy snout, short, gray fur that can be brushed in any direction, and they lack the large external ears that characterize the rodents.

Like most tunnel-dwellers, their vision is poor (one source said that their eyesight is so bad that they sometimes find their prey by bumping into it accidentally), but their senses of touch and hearing are well-developed.  Some sources say that they have a good sense of smell, but others disagree.  They scent mark their tunnels with a foul-tasting musk that’s manufactured in glands on their belly, but if their sense of smell is poor, this could be a warning to other species.  They communicate using a vocabulary of squeaks and clicks (some of which we can’t hear), and navigate underground using echolocation, like bats.  They are said to growl contentedly while feeding, which the BugLady thinks is charming.


Except during the breeding season, short-tailed shrews tend to be solitary and territorial.  Three or four litters are born each year, and the young of early litters may be parents themselves by the end of fall.  A three-year-old shrew is a very old shrew; winter mortality is high, and most don’t make it to their first birthday.


Add short-tailed shrews to the growing list of animals that are making themselves at home in the big city.  In a study of shrews reported in a blog called Urban Habitats, Virgil Brack, Jr writes about short-tailed shrews nesting in a vegetable garden, on an island in a parking lot, and in a crabapple tree in Cincinnati.  He told of one shrew that entered a garage and fed on a package of hamburger stored there (captive shrews love beef).  Brack also noted that short-tailed shrews are known to come to bird feeders.  Shrew tunnels are common in the snow below sunflower feeders, and it’s not known whether they are preying on invertebrates found there or feeding on the seed itself, but caches of corn have been found in the wild.


The BugLady regrets that the only pictures she has of short-tailed shrews are of dead ones (dead insects can often be posed to look like live insects, but alas, a dead shrew only looks like a dead shrew).  The BugLady figures that the dead shrews she finds have simply run out of gas; alternatively, that they were killed by predators that were subsequently discouraged by the shrew’s chemical defenses.  This article from the National Park Service offers another interesting explanation for shrew die-off in the section titled “Live Fast, Die Young, Leave a Smelly Corpse” (https://www.nps.gov/articles/netn-species-spotlight-short-tailed-shrew.htm).


The Missouri Department of Conservation puts out lots of great material about wild animals.  See https://mdc.mo.gov/blogs/discover-nature-notes/no-taming-shrew for some good pictures of short-tailed shrews, plus an overly-lurid video whose narrator is having way too much fun.


Wikipedia tells us, perhaps unnecessarily, that short-tailed shrews cannot be domesticated.


Kate Redmond, The BugLady

Bug of the Week archives:

Bug o’the Week – Water Penny Redux

Howdy, BugFans,


In the spirit of New Year’s Eve, here’s a rerun about a really spiffy little aquatic insect, revised from 10 years ago with some new words and pictures and also a correction.  In the original episode, the BugLady erroneously referred to adult water penny beetles as riffle beetles, but they aren’t riffle beetles (despite the fact that they hang out near riffles); true riffle beetles are members of the nearby family Elmidae.


Scooping for aquatic invertebrates is a great “gateway” to nature studies for many people – who knew that the world below the water’s surface was peopled by such an amazing bunch of critters!


Whether tadpole, fairy shrimp, leech, snail, planarian, or one of the myriad insects for whom the water is either a temporary nursery or a permanent home, aquatic animals face some common challenges.  They need a way to breathe, eat and locomote under water.  They need shelter from predators, a habitat that fills their needs, and a plan for overwintering.  And if an animal lives in swift currents, it has one more problem – staying in one place.  Some inhabitants of moving waters are streamlined, some attach with glue or silk, and others (like the sculpin that faces upstream with its fins braced against adjacent rocks) have structural adaptations to grab their surroundings so they don’t end up downstream.

Water penny beetles are in the family Psephenidae, a family whose immature or larval stage is much better known than its adult stage.  Adults – hairy, quarter-inch beetles https://bugguide.net/node/view/131447/bgimage – can be found in the water or basking on rocks and logs just above the water line, and also, according to Voshell, in his outstanding A Guide to Common Freshwater Invertebrates of North America, on rocks on wave-washed lakeshores.  There are 16 species of water pennies in North America; fewer than three hundred species occur world-wide, and the greatest diversity is found in the Orient.


Called water pennies for their shape and color, the larvae look like tiny, oblong suction cups https://bugguide.net/node/view/477142/bgimage dressed in camouflage.  They live underwater on rocks in rapid currents – an unusual habitat for a beetle larva, but one that offers some protection from predators (we have trouble finding them, but it’s said that trout don’t).

[Etymology alert: the official name for the larva’s shape is “platyform” – “platy” means “flat.”  Platyform is somewhat synonymous with “onisciform,” a word that refers to the flattened body shape of a wood louse (or sow bug or pill bug or roly-poly or potato bug or whatever regional name you learned as a kid).  Interested in the etymology of entomology? See https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1001&context=onlinedictinvertzoology].


Head and mouth are located at fore end, and filamentous gills are found at the aft end https://bugguide.net/node/view/207646/bgimage (great series of pictures).  Swift currents tend to be oxygen-rich, and the gills of water pennies grab dissolved oxygen from the active waters they live in (they also have spiracles for taking air in ala terrestrial insects).  Water pennies are indicators of waterways that are high in oxygen and low in pollution.


The claws on a water penny’s tarsi (feet) help it latch onto rock surfaces, and the “plates” that make up the tops of its body are flexible, allowing it to mold to the shape of a rock so that water flows over it.  The edges of the plates are fringed with hairs that enhance its grip.  It’s not physically suctioned to the rock, just very streamlined.


A female water penny beetle crawls “below-decks” into the swift currents to lay her eggs on the lower surfaces of algae-covered rocks, though she may deposit eggs just above the water’s surface, too.  The hairs on her body hold a film of air for her to breathe.


The larvae of some species are marginally social, tolerating nearby larvae, but they’re mostly solitary.  In colder climates, water pennies may take two years to mature, but they usually metamorphose into adults the next year.  They pupate in damp spots on land near the water’s edge or in air-filled chambers underwater, beneath that wonderful larval skin.


Adult water penny beetles’ basking days are brief, and they probably don’t eat (not much is known about them).  Water penny larvae are classed, diet-wise, as “scrapers” that ingest the algae and diatoms that live on rocks (a moderate algal film is desirable, but a thick algal mat is not water penny-friendly).  Voshell says that to this end, they are well-adapted.  Their cup-shaped jaws have a sharp inner edge to dislodge food, similar to a paint scraper, and hairs at the base of the jaws to help push the dislodged material into their mouths.  Other sources say that they have scrapers on their legs.  They are light-sensitive, clinging by day to the lower surfaces of rocks, migrating at night to the upper surfaces of rocks where the more nutritious algae grow.


So, in summary, these 6 mm critters live in strong currents and are the epitome of “streamlined.”  They don’t get swept away, and under the cover of their “shell,” the material that they scrape and loosen to eat doesn’t get swept away either, because it’s trapped.  What happens under a water penny, stays under a water penny.


Kate Redmond, The BugLady

Bug of the Week archives:

Member Guide to Winter at Riveredge

Trail Update January 24, 2020

Presently, we’re seeing a mix of snow and rain and temperatures in the mid-30’s. Snowshoes may work better than cross country skis; the snow is likely too warm for skis to glide. Join us Friday night for our Candle-lit Hike! Due to expected snowfall, the Riveredge Visitor’s Center will be open for snowshoe rental Saturday 1/25 from 9:00am – 4:00pm and Sunday 1/26 from 12:00pm – 4:00pm. Bring your skis and snowshoes (or rent snowshoes from Riveredge – free to all access members and explore!

Winter Trails

Winter provides exciting exploration opportunities, as some of the vulnerable trail areas that are otherwise off-limits to foot trafffic are able to be explored once the ground is frozen (see trail map below). We ask that anyone wearing boots or snowshoes walk on either side of identified ski trails in wintertime. Our trails are plenty wide, offering space for everyone to explore in their preferred manner. Trail conditions  are checked by Riveredge staff on a regular basis. Consult the Visitor’s Center for suggested trails and current snow conditions.

Checking out Snowshoes

At Riveredge, snowshoes are free for All Access Members to checkout for use on the Riveredge property and are able to be checked out when we have in excess of 6 inches of new fluffy snow or 4 inches of packed snow. Without sufficient snow, snowshoes will be damaged by digging into the gravel beneath the snow (plus it would probably be easier in boots anyway). Snowshoes are checked out on a first come, first served basis, and can be reserved ahead of time for events. Please affix snowshoes to your boots outside at the head of the trail; do not walk in snowshoes indoors or on brick, gravel, or wooden structures such as the back deck as this damages both the surface and the snowshoes. Snowshoes are available for checkout and must be returned before the building closes and for special events when the building is open (such as Friday Night Candle-lit Hikes).

Pop Up Hours

The Riveredge Visitor Center is generally closed on Saturdays and Sundays in winter, however if we have a decent snowfall and anticipate people having interest in checking out snowshoes, we will have weekend pop-up hours in the Visitor Center.

Winter Trail Map

Bug o’the Week – The Twelve Bugs of Christmas 2019

Season’s Greetings, BugFans,

Let’s celebrate the (almost bugless) Season with a dozen bugs that were photographed this year.  Down through the centuries, various regional versions of the classic Christmas carol have included hares a-running, ducks quacking, badgers baiting, bulls a-roaring, biting cows, bears a-beating, cocks a-crowing, asses racing, starlings, plovers, goldspinks (goldfinches), sides of meat, ponies, deer, stalks of corn, cheese, windmills, and an Arabian Baboon.  Never any bugs, though, so it’s up to us.

The BugLady wondered (innocently) if this BUMBLE BEE TRIO was sharing body heat one afternoon in mid-October, but BugFan Thelma explained the facts of life.  Even though the air was cool and their season was winding down, the two, smaller male bees still had hopes of a final tryst. We can all help track the range of bumble bees in Wisconsin by sending our bumble bee pictures, ID’d or not, to http://wiatri.net/inventory/bbb/.

WHITE SLANT-LINE MOTH – Moccasin-flowers/Pink lady’s-slipper orchids are typically pollinated by native bumble bees that, lured to the flower by color and odor, push their way into a slit in the slipper, hoping (in vain) for a tasty reward.  The moth may be biting off more than it can chew.

GOLD-BACKED SNIPE FLY – Is there a more elegant fly than this one?

NURSERY WEB SPIDER on tiptoe.  The Nursery web spider family (Pisauridae) includes the fishing spiders, but not all Pisaurids hang around the water’s edge (the BugLady once found a nursery web spider in her rhubarb).  They don’t spin trap webs; they find prey as they move across the landscape.  Their name comes from the shelters females make (and guard) for their egg cases.

The BugLady stalks SIX-SPOTTED TIGER BEETLES – small, emerald sparks on dirt trails – as they stalk spiders and small insects.  Some beetles don’t get the memo; there are two, four, six, and eight-spotted SSTBs.  The Audubon Society Field Guide to North American Insects and Spiders says that they fly ahead on the trail and then turn to face us, but the BugLady has an awful lot of pictures of the rear ends of SSTBs.  Read more about these great beetles at https://uwm.edu/field-station/tiger-beetles-revisited/.

FORKTAIL AND LESTES – the first Spreadwing (Lestes) damselfly that the BugLady saw this spring was a Slender Spreadwing dangling in the clutches of a mature female Eastern Forktail (the slate-blue damsel on the right).  Forktails are tough – a few days later, the BugLady photographed another forktail holding a Powdered Dancer, also larger than she was.

ROBBER FLY – Isn’t she spectacular!!  A fly this spectacular should really have a common name, but she doesn’t (although one photographer calls her an Orange robber fly).  She’s Asilus sericeus, an inch long robber fly that’s found in the eastern half of the country, often dining on butterflies and moths that have come in to nectar on flowers.  The BugLady is always blown away by those long, angular legs.  Starting soon – a three-year Citizen Science project designed to find out more about the distribution of robber fly species in Wisconsin.  The BugLady will post more info later.

Every fall the BugLady gets questions about the large, flightless, slow-moving MELOE BEETLE, a.k.a. Oil beetle or Short-winged Blister Beetle.  Look but don’t touch – they’re named “blister beetle” for a reason https://uwm.edu/field-station/blister-beetle/.  When they’re alarmed, Meloe beetles flop over and play dead, but they also ooze caustic stuff from their leg joints, so don’t touch the “dead” ones, either.

COMMON WOOD NYMPHS emerge in early July and fly around the grasslands into September.  We can’t appreciate their nuanced coloration as they pass (there’s some variation https://bugguide.net/node/view/1551172/bgimage, and https://bugguide.net/node/view/1173370/bgimage), but they really are monochromatic marvels, painted with shadow and texture.

SCORPIONFLIES are not in the fly order Diptera but in the order Mecoptera and the family Panorpidae.  The BugLady often finds these jumpy little insects on leaves that have bird poop on them – they are mostly scavengers that feed on droppings and dead/dying animal matter (they’ll even rob spider webs) as well as pollen and nectar.  This is a CSI bug – they will visit corpses, and their presence indicates that the body is fresh.  Both ends are interesting – the face has a conspicuous elongation called a rostrum, and although the males’ reproductive structures look like a scorpion’s tail https://bugguide.net/node/view/1495212/bgimage, they’re harmless. For more information https://uwm.edu/field-station/scorpionfly-revisited/.

At just under an inch in length, EASTERN AMBERWINGS are the smallest commonly-occurring dragonfly in Wisconsin (there are scattered populations of the even-smaller Elfin Skimmer http://wiatri.net/inventory/odonata/SpeciesAccounts/SpeciesDetail.cfm?TaxaID=156).  Many of our damselflies are longer, but they are far slimmer than the amberwing.  The BugLady finds it extraordinarily easy to take out-of-focus shots of amberwings.

GREEN STINK BUG: Note that the BugLady said that this is an “almost bugless” season.  Every year at about this time, the BugLady is visited by some insect, usually a mosquito, that should have been dead weeks ago.  Oh, the BugLady gets that the small, cold-tolerant Chironomid midges will dance in the air deep into fall, but it’s been snowy and extra-cold around here, folks, since the beginning of November (a week ago, right after the BugLady’s alarm went off, the TV weather guy announced that it was 3 degrees out.  She reacted appropriately).  So where had this Green stink bug, photographed outside the front door on November 27, been hanging out?  Or the spectacular Herald moth https://bugguide.net/node/view/1614972/bgimage that landed near her computer on November 23?  Or the crane fly that she found on December 12 in the sink? Or the spider whose web descended from the conifers to her windshield wiper on the balmy (37 degree) morning of December 21?  A Christmas Mystery.

Best Wishes for the New Year.

Kate Redmond, The BugLady

Bug of the Week archives:

Bug o’the Week – Horsefly

Howdy, BugFans,

The first rule of finding insects is “Look on flowers.”  Flowers provide a place to rest, as well as a place to eat and be eaten.  The second rule is “if you see an insect that’s really still (or in an odd position), look for a predator nearby.”  So, when the BugLady spotted a horizontal horse fly, she knew that something was afoot, and she soon located the ambush bug above and to the left of the fly (the fly’s eyes were a bonus).

Back in November of ‘aught-eight,’ the BugLady wrote briefly about horse flies in a survey of biting flies https://uwm.edu/field-station/a-few-flies/.  It’s a group that we love to hate, but hey, it’s December, and we can consider them cerebrally rather than emotionally.

Horse flies are in the fly family Tabanidae, which also includes the deer flies.  One source noted that while both horse and deer flies buzz on approach (deer flies’ whine is higher-pitched), horse flies aim at bare skin below the knees, and deer flies like the back of your neck.  The BugLady, whose field clothes are long pants and short sleeves, is going to have to mull that one over a bit.  According to bugguide.net, colloquial names include “Bulldog Flies, Clegs, Yellow Flies of the Dismal Swamp, Greenheads, Gad Flies, and Copper Heads.”  And undoubtedly other names that wouldn’t make it past the NBC censor.

There are about 4,500 Tabanid species worldwide – 350 in North America.  They’re found around the globe except for Hawaii, Greenland, Iceland, and the Polar Regions.  Our most familiar horse flies are in the genus Tabanus (pronounced Ta-BAY-nus), which has about 100 representatives in North America.  They’re often encountered around permanent wet/moist-lands because that’s where their somewhat aquatic offspring live, but they can be found from deserts to mountaintops.

Tabanids tend to be chunky flies, and some of them, at an inch-plus in length with a two-inch wingspan, are sizeable.  Their eyes are sometimes described as “bulging” (male flies have those huge, wrap-around eyes; females’ eyes are separated).  Deer flies tend to be more colorful than the usually-drab horseflies (but read on).

Male horse flies feed on nectar and pollen and don’t have the equipment to bite.  Females drink nectar, too, but they also need a blood meal (mostly from a mammal) to help them produce eggs.  So they ambush passers-by, zeroing in on large, dark-colored, moving objects that give off a cloud of CO(including motor vehicles, says Eric Eaton, in The Kaufman Field Guide to Insects of North America) (clouds of deer flies around the side mirrors of slowly-moving cars are a common sight in July in the habitats where the BugLady hangs out).

Wikipedia describes their mouthparts as “a stout stabbing organ with two pairs of sharp cutting blades, and a spongelike part used to lap up the blood that flows from the wound.  Anticoagulant saliva keeps the blood flowing, sometimes long after the fly has departed.  Some females may need a second meal or are disturbed during the first meal, and it’s in biting a second victim that she may transmit diseases (the list of pathogens isn’t long, and human infection is rare here in Wisconsin).  Some people are allergic to the bites, though, and cows that are under attack by Tabanids are not contented – both weight gain and milk production suffer.

Horse flies are not without predators – birds eat both adults and larvae; nematodes and wasps parasitize the larvae, and adults are captured by solitary wasps to provision their egg caches and by spiders https://bugguide.net/node/view/1688544/bgpage.

We swat at them without really looking at them, but if we didn’t know what they do for a living, we might notice that they’re pretty a handsome and diverse bunch of flies……  https://bugguide.net/node/view/1090460/bgpage, and

https://bugguide.net/node/view/1638079/bgpage, and

https://bugguide.net/node/view/285005/bgpage, and

https://bugguide.net/node/view/928300/bgpage, and

https://bugguide.net/node/view/428918/bgpage, and

https://bugguide.net/node/view/1522330/bgimage, and


…and that they have eyes that macro photographers love,

https://bugguide.net/node/view/967345/bgpage, and

https://bugguide.net/node/view/327405/bgimage, and

https://bugguide.net/node/view/951612/bgpage, and

https://bugguide.net/node/view/241723/bgpage, and

https://bugguide.net/node/view/123186/bgpage, and


(Why?  See https://uwm.edu/field-station/the-eye-of-the-fly/.)

Males chase females aerially after spotting them with those magnificent eyes.  She lays her eggs in clumps that may contain as many as 1,000 eggs in several layers.  Egg masses are glued to vegetation, rocks, twigs, etc. over the water; the BugLady usually finds them on cattail and blue flag leaves.  The tiny larvae are equipped with a spine that helps them exit the egg, and when they hatch, the larvae fall into the water (deer flies) or onto moist ground (horse flies).  There they stay, sometimes for several summers, especially in the north, feeding on small, soft-bodied insects and crustaceans, subduing them by biting them and injecting a venom https://bugguide.net/node/view/275578/bgpage (and like their elders, they’re capable of delivering quite a bite, themselves, when handled carelessly).

Horse flies have been bothering people since there have been people, and if you’re on board with the idea that some of the dinosaurs were actually warm-blooded, ancestral horse flies may have fed on them, too.  Aeschylus, a Greek playwright who died around 456 BC, wrote that horse flies drove people to madness.

The BugLady indulged in some picture-keying, which is unreliable but is so much fun when done responsibly.  She thinks that the ambush bug’s victim may be Tabanus marginalis, which bugguide.net calls “the most common biting fly throughout the world” (but has only three pictures of).  It’s a mostly-northern species with disjunct populations along the Appalachians, and it likes cool, wooded swamps.

The horse fly on the gravel path could be Tabanus nigripes, whose larvae are at home in wet areas that contain lots of organic material, like drainage ditches.  The Tabanidae of Florida, by Jones and Anthony, tells us that “in recreational areas adjacent to lakes where livestock is not present, this species is reported to be a serious threat of man.”

The horse fly on the green leaf is (possibly) Tabanus vivax.  One source says the larvae like boggy habitats, but a 1905 publication calls it the River horsefly and says that the larvae have been found in riffles.

The robust little, bullet-shaped fly with the dark stripe on its abdomen, sitting on a wood boardwalk, is probably Hybomitra illota, a horse fly of more northern orientation (mid-America, north).  The BugLady found an interesting paper by P.D. Taylor and S.M. Smith in Medical and Veterinary Entomology about the breeding behavior of males.  Under certain weather conditions, males aggregate in large groups at “mating areas.”  Their behavior is somewhat similar to the lek behavior of some birds.  Hybomitra illota is known to bother humans.

But not in God’s Country in December.

Kate Redmond, The BugLady

Bug of the Week archives:


Sue Haislmaier and her husband Dan recently attended the Barn Dance at Riveredge in October with her daughter’s family who was visiting from Montana. Following their visit, Sue shared the following testimony of her family’s connection with Riveredge through the years. A connection that continues today…..

“… all three of our kids were involved at Riveredge and are now
environmental advocates as adults. My grandkids know me as
the grandparent that likes to explore outside when we visit them.

I recently looked at old family slides and found a couple from the
year our son found the Yule Log around ‘82. We still have the
slice of log cookie memento from that find.

In those days I became known as “Nature Mom” with one of the
first naturalized yards in the area. I have served as a volunteer
Teacher Naturalist at Riveredge since the late ‘70’s and continue
to teach maple syruping program in the spring. I served on the
board of directors in the ‘80’s as well as chaired and participated
in many events throughout the years. The kids remember me
at a Halloween Hike as “a leaf pile” when I would rise from a
heap on the ground in my camouflaged cape to give a lesson on
composting and worms.

Riveredge holds a dear place in my heart and mind. Knowing
that, my kids gifted me with a tree for my birthday this year that
will be planted in the spring, I look forward to a place on the
landscape to visit frequently.”

~ Sue Haislmaier, Riveredge Kid since 1968


You can help ensure that even more families have the opportunity to make memories like these in the coming year and decades. Support the passing of the torch and the next generation of environmental stewards. By making a gift to the annual fund, your generosity will do just that. Visit www.riveredgenaturecenter.org/donate to make your charitable contribution this holiday season.

On behalf of everyone at Riveredge Nature Center, thank you for being a part of the family!

Bug o’the Week – Ninebark – a Bug Magnet

Greetings, BugFans,

A few years ago, when the BugLady wrote about the ninebark leaf beetle (Calligrapha spiraea) https://uwm.edu/field-station/rorschach-beetles-family-chrysomelidae/, she made a mental note to pay more attention to ninebark (Physocarpus opulifolius) during its blooming period.  Ninebark?  The way the BugLady heard the story, the shrub’s name comes from the German word “nein” for “no,” a reference to the fact that the smooth bark of the young branches looks like no bark at all (some non-German botanist eventually rearranged the vowels so that they made sense to him).  Anyway, a ninebark in bloom is a heap of beautiful flowers – opulifolius, indeed – and this year she watched some ninebarks that were humming with insects.  More than twenty species, in fact, most of them nectar-feeders!

Yes, it is reminiscent of that old-time favorite Bridal wreath, which is also in the rose family.

There were two species of SOLDIER FLIES, including the spectacular, green Odontomyia cincta.  Soldier flies are an interesting bunch of often-sluggish flies (family Stratiomyidae) who fold their wings over their backs like a closed scissors and whose antennae are “Y”-shaped.  The larvae develop in damp-to-wet habitats; spindle-shaped aquatic larvae often float at the surface, breathing through tubes in their posterior (https://uwm.edu/field-station/soldier-fly/).

At least three species of SWEAT BEES were there.  They also come in brown, and in green with a stripy abdomen.  These small, solitary bees are important pollinators of both native plants and (imported) agricultural crops like alfalfa.  The green one is in the genus Augochlora – or maybe Augochlorella or Augochloropsis; the one with the red abdomen is in the genus Sphecodes.  And yes, they are attracted to sweat, landing on your skin to lap sweat up with their short tongues, sometimes stinging as they are brushed off.  Happily, the Schmidt Sting Pain Index ranks them as the least painful of all stinging insects.

Sweat bees beware – the beautiful, little NOMADA bee has you in her sights!  Female sweat bees make nest tunnels and provision chambers within them for their eggs.  Nomada bees find those caches, lay an egg within, and her larvae eat the food that was stashed by the hard-working mining or sweat bee.  It’s called kleptoparasitism/cleptoparasitism.  For more about Nomada, see https://uwm.edu/field-station/spotted-nomad-bee/.

Male MOSQUITOES are vegetarians, sucking nectar from flowers and imbibing plant sap and aphid honeydew.  Females are, too, except when those species that do need a protein boost in order to lay their eggs must find some blood.  Not all species do, and some only look for a blood meal when they want to lay a second brood.  We love to hate them, but they are (grudgingly) highly sophisticated organisms that are excellent at what they do.

The BugLady always gets a kick out of finding the odd-looking, knobby-kneed MOLORCHUS beetles (Molorchus bimaculatus, probably), members of the Long-horned beetle family Cerambycidae.  She finds them on white flower heads in spring, disappearing into the flowers head first as they feed.

The other Cerambycid she saw was PIDONIA RUFICOLIS (probably), a widespread eastern beetle about which nobody says much of anything.

The extravagant VIRGINIA CTENUCHA MOTH is a largish (wingspread 2”), day (and night)-flying moth that’s frequently mistaken for a butterfly.  Some references place them in a group called the “wasp moths,” which includes species that are more obviously wasp-mimics than the Ctenucha is.  Adults are nectar-sippers; caterpillars grow up on a variety of grasses, sedges, and irises.  The “C” is silent.

FLESH FLY – what an evocative name.  It was (mostly) earned by the larvae, which are scavengers on decaying organic matter, dung (and open wounds), but the tweedy adults aren’t blameless.  Along with nectar, they sponge up fluids that result from the decay of dead plants, animals, and dung https://uwm.edu/field-station/flesh-fly/.

There are about 6,000 species of SYRPHID FLIES in the world (813 in North America).  These bee mimics land lightly on flowers (they’re also called Hover Flies and Flower Flies) to glean pollen and nectar.  There were several species on the ninebark.

Last, but not least, the BugLady saw six species of BUTTERFLIES – Red admiral, American Lady, Red-spotted Purple, Monarch, Viceroy, and Spring Spring Azure (not a typo – there are Spring Spring Azures and Summer Spring Azures).  Ninebark bloomed in time to support an emerging generation of Red Admirals – the BugLady counted more than 25 on one shrub.

Also seen were a Zelus assassin bug, a soldier beetle, honeybees, ants, and long-legged flies

Kate Redmond, The BugLady

Bug of the Week archives:

Bug o’the Week – Three More Bluets

Greetings, BugFans,

Seasoned BugFans know that the BugLady can’t go too long without writing about Odonates.

Quick review: Dragonflies and damselflies are in the order Odonata.  Dragonflies tend to be bigger and bulkier than damselflies, with wrap-around eyes that touch at the top of the head in most families, and with wings that are held out at about 90 degrees at rest.  Damselflies tend to be slimmer and smaller (though our longest damsels are longer than our smallest dragons), with eyes on the sides of their heads like a hammerhead shark, and with wings held over their backs or in a “V” at rest.  They’ve been around for more than 250 million years.

Bluets are damselflies in the Narrow-winged/Pond Damsel family Coenagrionidae.  As a group, the Narrow-winged damselflies are found near a variety of permanent, unpolluted wetlands with still-to-slow waters.  They lay their eggs (mostly) in submerged vegetation, and their aquatic offspring, naiads (“nymphs,” if you must, but never “larvae”) clamber around in underwater debris or on plants, ambushing the small invertebrates that swim by.  Adults are often found in or on the edges of stands of grasses, cattails, reeds, etc., where they are concealed from their predators (which include larger damselflies and dragonflies).  They prey on flying insects, and their forays are usually short ones.

Coenagrionidae is a big family of small damselflies (3,000 species – 135 in North America), represented in Wisconsin by dancers, forktails, bluets and sprites.  The BugLady wandered through the other genera of Pond damsels recently, and it took her breath away:

Red damsels – https://bugguide.net/node/view/402209/bgpage,

Black and white Damsels https://bugguide.net/node/view/241908/bgpage,

Aurora Damsels – https://bugguide.net/node/view/1616337/bgimage and https://bugguide.net/node/view/1309087/bgimage,

Painted Damsels – https://bugguide.net/node/view/1373017/bgpage,

Swamp Damsels – https://bugguide.net/node/view/1637415/bgpage,

Yellowfaces – https://bugguide.net/node/view/1638137/bgimage,

Firetails – https://bugguide.net/node/view/522811/bgimage,

and this little beauty – https://bugguide.net/node/view/916471/bgpage.

Road trip.

Many bluets are habitat generalists, but others are specialists.  Although they’re sometimes found far from water, they mostly live near the wetland that produced them.  Some male bluets are easy to identify, like this amazing Vesper Bluet (https://bugguide.net/node/view/437458/bgimage), but most are not, unless you have a net, and a hand lens with which to view the claspers/terminal appendages.  Photographs are usually inadequate for the task, so the BugLady has a big collection of “bluet X” pictures and, because photographers like to label their pictures, she undoubtedly has some “hastily-identified” bluet pictures, too.  Females, less flashy than males, can be even more confusing – they often come in a few color forms, and some individuals even have male coloration.

Visually (for “ease” in identification, not taxonomically) the three dozen or so species of bluets in the American bluet genus Enallagma are divided into four groups, based on the amount of blue on the male’s abdomen – “blue” bluets, “black” bluets, “intermediate” bluets, and “other” (in our neck of the woods, “other” means the dazzling Rainbow, Orange, and Vesper Bluets).  Seventeen genus members occur in Wisconsin, plus two species of Eurasian bluets in the genus Coenagrion.

Remember – there isn’t any blue pigment.  A bluet’s blue is “structural” – light bounces off special cells under the cuticle, and the wavelength our eye receives it as is aqua blue.

Without further ado, here are three common damsels that brighten the BugLady’s path from early-summer through mid-fall:


The TULE BLUET (Enallagma carunculatum) is found across the continent from southern Canada into Mexico near ponds, lakes of all sizes, and slow portions of streams, especially those with bulrushes growing along the edges.  It can tolerate moderately salty or alkaline water and is most common in the first half of summer.  Adults eat a lot of mayflies, and they sometimes pluck a sitting insect off its perch.

It’s a “mid-type bluet,” with narrow-but-noticeable blue rings around its abdomen.  Female Tule Bluets are blue or tannish, and to the BugLady’s eye, their colors have a pearly finish.

Males defend territories near the water’s edge, and after mating, he continues to grip her while she oviposits in the stems of bulrushes and other emergent plants (“contact guarding”).  Bob DuBois tell us in Damselflies of Minnesota, Wisconsin & Michigan that Tule Bluets are able to hybridize with Familiar Bluets and River Bluets.

[Etymological Aside: Tule (pronounced too-lee) is a common name given to several species of bulrushes that grow in marshes.  According to Wikipedia, it comes from a Nahuatl/Aztec word (“tollin”) that was adopted by the Spanish during their conquest of Mexico and applied to similar plants they found in California wetlands in the 1500’s.  The old California saying, “out in the tules” is akin to “out in the boondocks” (“boondock,” in turn, comes from a Tagalog/Philippine term for mountain or remote area).]

STREAM BLUETS (Enallagma exsulans) are “black-type bluets” that grace the edges of streams, rivers, and sometimes ponds starting in early summer (the BugLady photographed a female Stream Bluet at Spruce Lake Bog, and it took a few spins of her mental Rolodex to realize what she was looking at because – no stream).  They’re found in the eastern half of the country and they can be abundant.  DuBois says that they are “often found in the company of dancers (the damselfly variety of dancers, that is),” and that’s certainly true at Waubedonia Park where, at times, two out of every three damselflies seems to be either a Stream Bluet or a Powdered Dancer.

In a group where the females are often dull-colored, the lime green females with their tan/gold shoulder and eye stripes are spectacular.  His 9th abdominal segment is all blue, and the 8th is blue with a dark “V-shaped” notch on top; unlike many female bluets, she also shows blue on the tip of her abdomen.

They have a remarkably long mating period for a damselfly, averaging 1 ¼ hour.  Females often submerge completely while ovipositing in plant stems, sometimes for as long as 30 minutes – he may accompany her part way, but he usually releases her before he goes under.

The BugLady enjoys seeing FAMILIAR BLUETS (Enallagma civile) on her walks in late summer, after most other bluets have faded away.  Although the size of this “blue-type bluet” is comparable to the other two (1 ¼” to 1 ½”), it seems “beefier,” and its claspers are distinctive enough to be recognizable in a photograph.

They like a variety of wetland types across most of the continent and throughout Central America.  They are not picky about water quality, and they are inveterate colonizers of newly-formed wetlands.

Single males spend most of their time near the water, and females are unceremoniously snatched up by males if they approach the water’s edge.  A tandem pair makes exploratory flights, looking for good habitat, before she oviposits.  Beck and Bick, in an article in the Southwestern Naturalist in 1963, wrote that “One Familiar Bluet pair oviposited above the water for 158 minutes, then the female went underwater and oviposited there for another 15 minutes. One female ovipositing at the surface saw her guarding mate eaten by a Giant Water Bug, but continued to oviposit even after the bug finished eating the mate and made several attempts to seize her.

Like those of the Tule and Stream Bluets, Familiar Bluet eggs hatch quickly, the youngsters grow fast, and they overwinter as late-stage naiads.

The BugLady gives Thanks for damselflies.

Kate Redmond, The BugLady

Bug of the Week archives: